Process for preparing hydrofluoroethers

ABSTRACT

Process for obtaining hydrofluoroethers of formula (I):  
     A-(R f ) n0 —CF(R f1 )—O—R h   (I)  
     wherein: n0 is zero or 1; R f  is a bivalent radical:  
     C 1 -C 20  (per)fluoroalkylene, optionally containing one or more oxygen atoms;  
     —CFW′O—(R f2 )—CFW—, wherein W and W′, equal or different, are F, CF 3 ; R f2  is a (per)fluoropolyoxyalkylene;  
     R f1  is F or a C 1 -C 10  (per)fluoroalkyl or (per)fluorooxyalkyl radical;  
     R h  is a C 1 -C 20  linear, branched, saturated or unsaturated alkyl, or C 7 -C 20  alkylaryl,  
     A═F, (R h2 O)—CF(R f4 )—, —C(O)F, wherein R h2 , equal to or different from R h , has the R h  meanings and R f4 , equal to or different from R f1 , has the R f1  meanings;  
     wherein a mono- or bifunctional carbonyl compound of formula (IV):  
     B—R f —C(O)R f1   (IV)  
     B being F or —C(O)R f4 , R f , R f1  and R f4  being as above, is reacted with at least one equivalent of a fluoroformate of formula (III)  
     R—OC(O)F  (III)  
     wherein R═R h  or R h2  as above defined;  
     in the presence of an ion fluoride compound (catalyst) and of a dipolar aprotic organic compound, liquid and inert under the reaction conditions.

[0001] The present invention relates to a catalytic process forpreparing hydrofluoroethers (HFE) in high yields and selectivity.

[0002] More specifically the present invention relates tohydrofluoroethers having one end group of the —O—R_(h) type whereinR_(h) is a saturated or unsaturated hydrocarbon group.

[0003] Processes to obtain hydrofluoroethers are known in the prior art.

[0004] U.S. Pat. No. 3,962,460 describes hydrofluoroethers and theirsynthesis. For example the CF₃—CF(CF₃)—OCH₂Cl, CF₃—CF(CF₃)—OCH₃compounds described in the patent are prepared by reaction ofdimethylsulphate, potassium fluoride and a carbonyl reactant in a largeexcess. The process has the drawback that the metal fluoride is used asa reactant, and significant amounts of reactants and inorganic salts,formed during the reaction, remain in the final mixture. These salts,must be disposed, as for example potassium sulphate. Moreover the yieldsof this process are not high.

[0005] Patent application WO 97/38962 describes a process for preparingHFE in dipolar aprotic solvents by the following reactants: a) a(per)fluorocarbonyl compound; b) fluorides, generally anhydrousmetalfluorides; in particular KF; c) tertiary or aromatic amines inamounts to neutralize the acid contaminants present in the reactionmixture, mainly HF; d) optionally a phase transfer catalyst. The soprepared mixture is then added to an alkylating agent, for examplemethyl sulphate, obtaining hydrofluoroethers. This process has thedrawback that metal fluoride amounts equal to at least thestoichiometric value, are used, with respect to the acylfluorides to bealkylated. Further the yields are high only when tertiary or aromaticamines, in the presence of an excess of alkylating agent, are used.Besides, as said for the previous patent, the mixture at the end of thereaction contains significant amounts of reactants and inorganic saltsto be disposed.

[0006] Patent application WO 99/37598 describes a process for preparinghydrofluoroethers by reaction of a fluoroalkoxide and an alkylfluorovinylether in a dipolar aprotic solvent. The drawback of thisprocess is that the two reactants must be prepared. The fluoroalkoxideis obtained in anhydrous environment by reaction of an acylfluoride withan excess of anhydrous metal fluorides, for example KF. The alkylfluorovinylether compound is obtained in two steps, by reaction of analcohol with a fluoroolefin and then dehydrofluorination of the obtainedcompound. The formation process of the fluoroalkoxide has the drawbackto use a high amount of a anhydrous metalfluoride per mole ofacylfluoride alkylate. The formation process of the alkylfluorovinylether has furthermore the drawback to use fluoroolefins,compounds not always available and often toxic.

[0007] Patent application WO 99/47480 describes a process for preparinghydrofluoroethers, wherein a perfluorocarbonyl compound is reacted withan alkylating agent R^(I)-F in the presence of an acid Lewis catalyst,for example SbF₅. The drawback of this process is that the catalysts canbe easily deactivated by impurities of the starting products and byreaction by-products, for example ethylene when R^(I)-F is CH₃CH₂-F, oralso by H₂O traces of polluting basic compounds. Furthermore themono-fluoroalkyl alkylating agent must be prepared. The alkylationreaction between the carbonyl fluorinated product and the R^(I)-Falkylating agent in the presence of the acid catalyst is an exothermalequilibrium reaction. The yields are good only by using a strong excessof alkylating agent R^(I)-F with respect to the carbonyl compound.Besides, the separation phase of the raw reaction product from thecatalyst can be difficult since, as said, the reaction is anequilibriumreaction and therefore the catalyst promotes also the reverseretrocondensation reaction. According to the Examples of this patentapplication the yields in hydrofluoroethers, starting from a perfluorocarbonyl compound and an alkylating agent, are high only when CH₃F isused as alkylating agent.

[0008] The need was felt to have available a process for preparinghydrofluoroethers having one —O—R_(h) end group, wherein R_(h) is asaturated or unsaturated hydrocarbon group, having the following featurecombination:

[0009] high condensation yields, even when R_(h) contains one or morecarbon atoms;

[0010] possibility of recycle of the catalyst;

[0011] separation of the hydrofluoroether condensation products bysimple techniques;

[0012] low environmental impact of the by-products to be disposed.

[0013] The Applicant has surprisingly and unexpectedly found a processof preparation of hydrofluoroether compounds solving the above technicalproblem.

[0014] An object of the present invention is a process for obtaininghydrofluoroethers of formula:

A-(R_(f))_(n0)—CF(R_(f1))—O—R_(h)  (I)

[0015] wherein:

[0016] n0 is zero or 1;

[0017] R_(f) is a bivalent radical:

[0018] C₁-C₂₀, preferably C₂-C₁₂, linear or branched(per)fluoroalkylene, optionally containing one or more oxygen atoms; or

[0019] —CFW′O—(R_(f2))—CFW—, wherein W and W′, equal or different, areF, CF₃; R_(f2) is a (per)fluoropolyoxyalkylene containing one or more ofthe following units, statistically distributed along the chain, (C₃F₆O);—(CFWO) wherein W is as above; (C₂F₄O), (CF₂(CF₂)_(z)CF₂) wherein z isan integer equal to 1 or 2; (CH₂CF₂CF₂);

[0020] R_(f1) is F or a C₁-C₁₀ linear or branched (per)fluoroalkyl or(per)fluorooxyalkyl radical;

[0021] R_(h) is a C₁-C₂₀, preferably C₁-C₁₀, linear, branched whenpossible, saturated or unsaturated when possible alkyl; or R_(h) isC₁-C₂₀ alkylaryl, optionally containing heteroatoms selected from F, O,N, S, P, Cl; and/or functional groups preferably selected from —SO₂F,—CH═CH₂, —CH₂CH═CH₂ and NO₂;

[0022] A=F, (R_(h2)O)—CF(R_(f4))—, —C(O)F, wherein

[0023] R_(h2), equal to or different from R_(h), has the R_(h) meanings;

[0024] R_(f4), equal to or different from R_(f1), has the R_(f1)meanings;

[0025] wherein a mono- or bifunctional carbonyl compound of formula:

B—R_(f)—C(O)R_(f1)  (IV)

[0026] wherein B is F or —C(O)R_(f4), R_(f), R_(f1) and R_(f4) being asabove, is reacted with at least one equivalent of a fluoroformate offormula:

R—OC(O)F  (III)

[0027] wherein R=R_(h) or R_(h2) as above;

[0028] in the presence of an ion fluoride compound which acts as acatalyst and of a dipolar aprotic organic liquid compound, inert in thereaction conditions.

[0029] The (C₃F₆O) unit of R_(f2) in R_(f) can be (CF₂CF(CF₃)O) or(CF(CF₃)CF₂O).

[0030] The reaction between the carbonyl compound (IV) and thefluoroformate (III) develops one CO₂ mole for equivalent of —C(O)R_(f1)or —C(O)R_(f4).

[0031] When the compound (IV) is bifunctional, i.e. B═—C(O)R_(f4), it ispossible to react the carbonyl compound with two fluoroformate (III)having a different R.

[0032] Preferably in formula (I) R_(f1) and R_(f4) in A, independentlythe one from the other, are F, CF₃.

[0033] Preferably when R_(f) is a (per)fluoroalkylene it is selectedfrom the following groups: —CF₂—, —CF₂CF₂—, —CF₂CF₂CF₂—, —CF₂(CF₃)CF—;when R_(f) contains one oxygen atom it preferably has the —CF₂CF(OCF₃)—meaning.

[0034] R_(f2) is a perfluoropolyoxyalkylene chain having number averagemolecular weight from 66 to 12,000, preferably from 100 to 5,000, morepreferably from 300 to 2,000.

[0035] Preferably the perfluorooxyalkylene chain of R_(f2) is selectedfrom the following structures:

[0036] a) —(CF₂CF₂O)_(m)(CF₂O)_(n)(CF₂CF(CF₃)O)_(p)(CF(CF₃)O)_(q)—;

[0037] b) —(CF₂O)_(n)(CF₂CF(CF₃)O)_(p)(CF(CF₃)O)_(q)—;

[0038] —(CF₂CF₂O)_(m)(CF₂O)_(n);

[0039] wherein:

[0040] m is comprised between 0 and 100 extremes included;

[0041] n is comprised between 0 and 50 extremes included;

[0042] p is comprised between 0 and 100 extremes included;

[0043] q is comprised between 0 and 60 extremes included;

[0044] m+n+p+q>0 and the number average molecular weight of R_(f2) beingin the above limits.

[0045] The perfluorooxyalkylene c) is preferred, wherein the m/n ratioranges from 0.1 to 10, n being differnt from zero and the number averagemolecular weight within the above limits.

[0046] Preferably R_(h) and R_(h2) have the following meanings:

—CH₃, —CH₂CH₃, —CH₂CH₂CH₃), —CH(CH₃)₂, —CH₂CH═CH₂.

[0047] The ion fluoride compound is any compound capable to generate ionfluorides when in the presence of dipolar aprotic solvents, attemperatures from 20° C. up to 200° C.

[0048] Examples of dipolar aprotic solvents are acetonitrile,dimethylformamide, glyme, ethylene polyoxides dimethylethers(PEO-dimethylethers); preferably tetraglyme and PEO-dimethylethershaving a number average molecular weight in the range 134-2,000 areused.

[0049] The ion fluoride compound is preferably selected from metalfluorides, in particular alkaline or alkaline-earth metal fluorides;AgF; alkylammoniumfluorides, alkylphosphoniumfluorides, wherein thenitrogen or respecively the phosphor atom can be substituted with one ormore C₁-C₈ alkyl groups, equal to or different from each other.

[0050] CsF and KF are the preferred catalysts.

[0051] Optionally the catalyst is supported, for example on a porousmaterial, such as for example Al₂O₃ or MgO.

[0052] The catalyst amounts, expressed in % by moles, are in the range0.1%-50% with respect to the mono- or bifunctional carbonyl compound offormula (IV).

[0053] As said, the reaction between the carbonyl compound (IV) andfluoroformate (III) takes place in the presence of a dipolar aproticorganic compound, liquid and inert in the reaction conditions. Saidorganic compound is for example acetonitrile, dimethylformamide, glyme,ethylene polyoxides dimethylethers (PEO-dimethylethers); preferablytetraglyme and PEO-dimethylethers having number average molecular weightin the range 134-2,000 are used.

[0054] The ratio by weight betwen the dipolar aprotic organic compoundand the ion fluoride compound can range from 1:100 to 100:1.

[0055] Optionally in the process according to the present invetiontertiary amines and/or phase transfer catalysts can be used. It has beenfound that these compounds facilitate the condensation reaction between(III) and (IV).

[0056] The reaction temperature in the process acording to the presentinvention is from 60° C. to 200° C. preferably from 80° C. to 150° C.

[0057] The pressure at which one oeprates can be the atmosphericpressure or higher, even up to 30 atm.

[0058] The formation of the reaction products can for example befollowed by monitoring in the time the pressure increase (CO₂formation), until the pressure remains constant.

[0059] The reaction time is from 1 h to 100 h, preferably from 6 h to 72h.

[0060] When the carbonyl compound (IV) is bifunctional, the reaction canalso take place in two steps. In the first step one fluoroformate mole(III) (R═R_(h)) is added for the first equivalent of carbonyl compound(IV). At the end of the reaction one mole of a different fluoroformate(R═R_(h2)) is added, to react the second equivalent of the carbonylcompound (IV). Alternatively the two fluoroformates can becontemporaneously added.

[0061] The yields are calculated as percent ratio between the obtainedHFE moles and the initial moles of the carbonyl compound (IV).

[0062] The process according to the present invention allows to obtainhigh HFE yields, generally higher than 70%.

[0063] Furthermore the selectivity, defined as percent ratio by molesbetween the HFE and the reacted carbonyl compound (IV), is generallyhigher than 90%.

[0064] At the end of the reaction the condensation products can beseparated from the raw reaction product by distillation or bydecantation. The skilled in the art, depending on the boiling points ofthe final products and the dipolar aprotic compound to be used, canselect the most suitable method.

[0065] It is thus possible to recover and reuse, even more times, thesuspension/solution of the ion fluoride compound in the dipolar aproticorganic compound. One can operate to maintain the suspension/solution ofthe catalyst in the condensation reactor: in this case the reactants arefed into the reactor and only the condensation products, optionally theunreacted compounds, are discharged.

[0066] The process according to the present invention can be carried outin a discontinuous or in a continuous way.

[0067] The carbonyl compounds (IV) can be prepared according to thedisclosures of the following patents: U.S. Pat. No. 3,113,967, U.S. Pat.No. 3,114,778, U.S. Pat. No. 3,250,808, U.S. Pat. No. 3,351,644, U.S.Pat. No. 6,013,795, U.S. Pat. No. 3,847,978, U.S. Pat. No. 6,127,498,U.S. Pat. No. 5,488,142, the patent applications in Italy Nos. MI 2003A000018, MI 2003A 000019 and MI 2002A 001365.

[0068] The fluoroformate compounds (III) are known in the art and can beprepared according to the disclosures of the patent GB 1,216,639.

[0069] The compounds prepared according to the present invention areused as refrigerants, foaming agents, solvents, lubricants, heattransfer and have a reduced environmental impact.

[0070] The following Examples illustrate with non limitative purposesthe present invention.

EXAMPLE 1

[0071] (CF₃O) (CF₃)CFCF₂OCH₃ Synthesis

[0072] 0.36 g of CsF in powder (2.4 mmoles) and 2.02 g of tetraglyme(CH₃O(CH₂CH₂O)₄CH₃) are introduced by dry-box in a 25 ml autoclaveequipped with pressure transducer and magnetic anchor. After havingremoved the uncondensable products by a vacuum system, 23 mmoles ofacyl-fluoride (CF₃O) (CF₃)CFCOF and then 23 mmoles ofmethylfluoroformate (CH₃OC(O)F) are condensed in the autoclave. Theautoclave is put in an oil bath maintained at the tmeperature of 100° C.After 36 hours the heating is turned out and the autoclave content istransferred into a vacuum system. By a trap-to-trap distillation withtraps maintained at the temperatures of respectively −110° C. and −196°C., 5.25 g of distillate are isolated in the trap at −110° C., whichanalyzed by GC, results to contain 84% by weight of the product (CF₃O)(CF₃)CFCF₂OCH₃. The alkylation yield as ratio between the obtained HFEmoles and the moles of the used carbonyl compound is 72%. The alkylationyield with respect to the converted acyl fluoride (selectivity) is 95%.

EXAMPLE 2

[0073] (CF₃O) (CF₃)CFCF₂OCH₂CH₃ Synthesis

[0074] One proceeds as in the Example 1 but by feeding 15 mmoles of thesame acyl-fluoride and 15 mmoles of ethylfluoroformate (CH₃CH₂OC(O)F).After trap-to-trap distillation 3.21 g of distillate are isolatedcontaining 87% by weight of the desired product with an alkylation yieldwith respect to the initial acylfluoride of 76%. The selectivity is 96%.

EXAMPLE 3

[0075] (CF₃O) (CF₃)CFCF₂OCH₂CH═CH₂ Synthesis

[0076] One proceeds as in the Example 1 but by feeding 15 mmoles of thesame acyl-fluoride and 15 mmoles of allylfluoroformate(CH₂═CHCH₂OC(O)F). After trap-to-trap distillation 3.76 g of distillateare isolated containing 95% by weight of the desired product with analkylation yield with respect to the initial acylfluoride of 81%. Theselectivity is 97%.

EXAMPLE 4

[0077] (CF₃O) (CF₃)CFCF₂OCH(CH₃)₂ Synthesis

[0078] One proceeds as in the Example 1 but by feeding 15 mmoles of thesame acyl-fluoride and 15 mmoles of isopropylfluoroformate((CH₃)₂CHOC(O)F) and the reaction time is brought to 48 hours. Aftertrap-to-trap distillation 4.35 g of distillate are isolated containing59% by weight of the desired product with an alkylation yield withrespect to the initial acylfluoride of 57%. The selectivity is 82%.

EXAMPLE 5

[0079] CH₃O—CF₂CF₂O(CF₂CF₂O)_(m)(CF₂O)_(n)CF₂CF₂—OCH₃ Synthesis

[0080] 0.77 g of CsF in powder (5.1 mmoles), 2.10 g of tetraglyme and4.09 g of diacyl-fluoride F(O)CCF₂O(CF₂CF₂O)_(m)—(CF₂O)_(n)CF₂C(O)F(IA)with number average MW (MN) 620, m/n ratio=4.3, functionality of theC(O)F end groups 1.82 (12 mmoles of acyl-fluoride end groups), areintroduced by dry-box in a 25 ml autoclave equipped with pressuretransducer and magnetic anchor.

[0081] After having removed the uncondensable products in a vacuumsystem (10⁻³ mbar) at −196° C., 20 mmoles of methylfluoroformate arecondensed in the autoclave. The autoclave is put in an oil bathmaintained at the temperature of 100° C. After 24 hours the heating isinterrupted and 2.0 g of methanol are condensed in the autoclave toesterify the unreacted acylfluoride groups. Then the gaseous phase (CO₂,HF) is eliminated in a vacuum system and the fluorinated phase isrecovered, washed with water. By ¹H-NMR and ¹⁹F-NMR analyses it resultsthat the reaction yield with respect to the initial acylfluoride is 90%.The selectivity is 100%.

EXAMPLE 6

[0082] CH₃CH₂O—CF₂CF₂O(CF₂CF₂O)_(m)(CF₂O)_(n)CF₂CF₂—OCH₂CH₃ Synthesis

[0083] 0.38 g of CsF in powder (2.5 mmoles), 2.04 g of tetraglyme and4.02 g of diacyl-fluoride (IA) of the Example 5 are introduced bydry-box in a 25 ml autoclave equipped with pressure transducer andmagnetic anchor. After having removed the uncondensable products in avacuum system (10⁻³ mbar) at −196° C., 19 mmoles of ethylfluoroformateare condensed in the autoclave. The autoclave is put in an oil bathmaintained at the temperature of 100° C. After 48 hours the temperatureis increased to 130° C. and it is let react for 24 hours. At the endheating is interrupted and 2.0 g of methanol are condensed in theautoclave. Then the gaseous phase (CO₂, HF) is eliminated by a vacuumsystem and the fluorinated phase is recovered, washed with water. By¹H-NMR and ¹⁹F-NMR analyses it results that the alkylation yield withrespect to the initial acylfluoride is 96%. The selectivity is 100%.

EXAMPLE 7

[0084] CH₂═CHCH₂O—CF₂CF₂O(CF₂CF₂O)_(m)(CF₂O)_(n)CF₂CF₂—OCH₂CH═CH₂Synthesis

[0085] 0.40 g of CsF in powder (2.6 mmoles), 2.03 g of tetraglyme and4.04 g of diacyl-fluoride (IA) of Example 5 and 2.05 g ofallylfluoroformate (19.7 mmoles) are introduced by dry-box in a 25 mlautoclave equipped with pressure transducer and magnetic anchor. Afterhaving removed the uncondensable products in a vacuum system (10⁻³ mbar)at −196° C., the autoclave is put in an oil bath maintained at thetemperature of 100° C. After 24 hours heating is interrupted and 2.0 gof methanol are condensed in the autoclave. Then the gaseous phase (CO₂,HF) is eliminated by a vacuum system and the fluorinated phase isrecovered, washed with water. By ¹H-NMR and ¹⁹F-NMR analyses it resultsthat the alkylation yield with respect to the initial acylfluoride is90%. The selectivity is 100%.

EXAMPLE 8

[0086] CF₃O—(CF₂CF₂O)_(m)(CF₂O)_(n)CF₂CF₂—OCH₃ Synthesis

[0087] 0.152 g of CsF in powder (1.0 mmoles), 1.0 g of tetraglyme and2.36 g of mono-acylfluoride CF₃O—(CF₂CF₂O)_(m)—(CF₂O)_(n)CF₂C(O)F (IB)with number average molecular weight (MN) 590, m/n ratio=4.45 andfunctionality of the C(O)F end groups 1.0 (4.0 mmoles of acyl-fluorideend groups), are introduced by dry-box in a 25 ml autoclave equippedwith pressure transducer and magnetic anchor. After having removed theuncondensable products in a vacuum system (10⁻³ mbar) at −196° C., 8mmoles of methylfluoroformate are condensed in the autoclave. Theautoclave is heated by an oil bath to the temperature of 100° C. andmaintained at this temperature for 48 hours. The reaction is followedchecking the internal pressure. When the reaction is over, 1.0 g ofmethanol are condensed in the autoclave. Then the gaseous phase (CO₂,HF) is eliminated by a vacuum system and the fluorinated phase isrecovered, washed with water. By ¹H-NMR and ¹⁹F-NMR analyses it is foundthat the alkylation yield with respect to the initial acylfluoride is97%. The selectivity is 100%.

[0088] By following during the reaction the pressure increase in thetime, due to the CO₂ formation, it has been noticed that the alkylationyield with respect to the initial acylfluoride is higher than 80%already after the first 8 hours, showing that the reaction gives highyields in the desired product also in short times.

EXAMPLE 9

[0089] CF₃O—(CF₂CF₂O)_(m)(CF₂O)_(n)CF₂CF₂—OCH₂CH₃ Synthesis

[0090] One proceeds as in the Example 8 but by condensing in theautoclave 8 mmoles of ethylfluoroformate. The autoclave is heated by anoil bath to the temperature of 100° C. and maintained at thistemperature for 48 hours and the reaction is followed by checking theinternal pressure. When the reaction is over, 1.0 g of methanol arecondensed in the autoclave. Then the gaseous phase (CO₂, HF) iseliminated by a vacuum system and the fluorinated phase is recovered,washed with water. By ¹H-NMR and ¹⁹F-NMR analyses it results that thealkylation yield with respect to the initial acylfluoride is 82%. Theselectivity is 100%.

EXAMPLE 10

[0091] CF₃O—(CF₂CF₂O)_(m)(CF₂O)_(n)CF₂CF₂—OCH(CH₃)₂ Synthesis

[0092] One proceeds as in the Example 8 but by condensing in theautoclave 8 mmoles of isopropylfluoroformate. The autoclave is heated byan oil bath to the temperature of 100° C. and maintained at thistemperature for 48 hours. The reaction is followed by checking theinternal pressure. When the reaction is over, 1.0 g of methanol arecondensed in the autoclave. Then the gaseous phase (CO₂, HF) iseliminated by a vacuum system and the fluorinated phase is recovered,washed with water. By ¹H-NMR and ¹⁹F-NMR analyses it results that thealkylation yield with respect to the initial acylfluoride is 90%. Theselectivity is 100%.

EXAMPLE 11

[0093] CF₃O—(CF₂CF₂O)_(m)(CF₂O)_(n)CF₂CF₂—OCH₂CH═CH₂ Synthesis

[0094] One proceeds as in the Example 8 but by condensing in theautoclave 8 mmoles of allylfluoroformate. The autoclave is heated by anoil bath to the temperature of 100° C. and maintained at thistemperature for 48 hours. The reaction is followed by checking theinternal pressure. When the reaction is over, 1.0 g of methanol arecondensed in the autoclave. Then the gaseous phase (CO₂, HF) iseliminated by a vacuum system and the fluorinated phase is recovered,washed with water. By ¹H-NMR and ¹⁹F-NMR analyses it results that thealkylation yield with respect to the initial acylfluoride is 98%. Theselectivity is 100%.

[0095] By following during the reaction the pressure increase in thetime, due to the CO₂ formation, it has been noticed that the alkylationyield with respect to the initial acylfluoride is higher than 80%already after the first 8 hours, showing that the reaction gives highyields in the desired product also in short times.

EXAMPLE 12

[0096] (CF₃)₂CFOCH₃ Synthesis

[0097] 0.38 g of CsF in powder (2.5 mmoles) and 1.02 g of tetraglyme areintroduced by dry-box in a 25 ml autoclave equipped with pressuretransducer and magnetic anchor.

[0098] After having removed the uncondensable products by a vacuumsystem, 15.6 mmoles of hexafluoroacetone and 16.7 mmoles ofmethylfluoroformate are condensed in the autoclave. The autoclave is putin an oil bath maintained at the temperature of 100° C. After 36 hoursthe heating is stopped and the autoclave content is transferred in avacuum system. By a trap-to-trap distillation with traps maintained,respectively, at the temperatures of −78° C., −115° C. and −196° C.,2.84 g of pure product are isolated in the trap at −115° C., with analkylation yield with respect to the initial hexafluoroacetone of 91%.The selectivity is 100%.

EXAMPLE 13

[0099] (CF₃O) (CF₃)CFCF₂OCH₃ Synthesis

[0100] 0.36 g of CsF in powder (2.4 mmoles) and 2.01 g of tetraglyme areintroduced by dry-box in a 25 ml autoclave equipped with magneticanchor. After having removed the uncondensable products by a vacuumsystem, 10 mmoles of acylfluoride (CF₃O) (CF₃)CFCOF and then 15 mmolesof methylfluoroformate CH₃OC(O)F are condensed in the autoclave. Theautoclave is put in an oil bath maintained at the temperature of 100° C.After 24 hours the heating is stopped and the autoclave content istransferred in a vacuum system; by a trap-to-trap distillation withtraps maintained, respectively, at the temperatures of −78° C., −110° C.and −196° C., 2.88 g of a raw product are isolated in the trap at −78°C.; they analyzed by GC, result to contain 93% by weight of (CF₃O)(CF₃)CFCF₂OCH₃, with an alkylation yield with respect to the initialacylfluoride of 100%.

EXAMPLE 14

[0101] (CF₃)₂CFCF₂OCH₃ Synthesis

[0102] One proceeds as in the Example 1, but by feeding 10.9 mmoles of(CF₃)₂CFCOF and 17 mmoles of methylfluoroformate CH₃OCOF. Aftertrap-to-trap distillation, 2.71 g of distillate are isolated containing72% by weight of the desired product with an alkylation yield withrespect to the initial acylfluoride of 71%. The selectivity is 95%.

EXAMPLE 15

[0103] CH₃O—CF₂CF₂O(CF₂CF₂O)_(m)(CF₂O)_(n)CF₂CF₂—OCH₃ Synthesis by Usingas Catalyst KF

[0104] The Example 5 is repeated but by using as catalyst KF (5.1mmoles), at the place of CsF and stopping the heating after 48 hours.

[0105] The alkylation yield with respect to the initial acylfluoride is85%. The selectivity is 100%.

1. Process for obtaining hydrofluoroethers of formula (I): A-(R_(f))_(n0)—CF(R_(f1))—O—R_(h)  (I) wherein: n0 is zero or 1; R_(f) is a bivalent radical: C₁-C₂₀, preferably C₂-C₁₂, linear or branched (per)fluoroalkylene, optionally containing one or more oxygen atoms; —CFW′O—(R_(f2))—CFW—, wherein W and W′, equal or different, are F, CF₃; R_(f2) is a (per)fluoropolyoxyalkylene containing one or more of the following units, statistically distributed along the chain, (C₃F₆O); (CFWO) wherein W is as above; (C₂F₄O), (CF₂(CF₂)_(z)CF₂) wherein z is an integer equal to 1 or 2; (CH₂CF₂CF₂); R_(f1) is F or a C₁-C₁₀ linear or branched (per)fluoroalkyl or (per)fluorooxyalkyl radical; R_(h) is a C₁-C₂₀, preferably C₁-C₁₀ linear, branched when possible, saturated or unsaturated when possible alkyl, or C₇-C₂₀ alkylaryl, optionally containing heteroatoms selected from F, O, N, S, P, Cl; and/or functional groups preferably selected from —SO₂F, —CH═CH₂, —CH₂CH═CH₂ and NO₂; A═F, (R_(h2)O)—CF(R_(f4))—, —C(O)F, wherein R_(h2), equal to or different from R_(h), has the R_(h) meanings; R_(f4), equal to or different from R_(f1), has the R_(f1) meanings; wherein a mono- or bifunctional carbonyl compound of formula: B—R_(f)—C(O)R_(f1)  (IV) wherein B is F or —C(O)R_(f4), R_(f), R_(f1), and R_(f4) being as above, is reacted with at least one equivalent of a fluoroformate of formula: R—OC(O)F  (III) wherein R—R_(h) or R_(h2) as above; in the presence of an ion fluoride compound (catalyst) and of a dipolar aprotic organic compound, liquid and inert under the reaction conditions.
 2. A process according to claim 1, wherein the (C₃F₆O) unit of R_(f2) can be (CF₂CF(CF₃)O) or (CF(CF₃)CF₂O).
 3. A process according to claims 1-2 claim 1, wherein in formula (I) R_(f1), and R_(f4) of A, independently the one from the other, are F, CF₃.
 4. A process according to claims 1-3 claim 1, wherein when R_(f) of formula (I) is a (per)fluoroalkylene, R_(f) is selected from the following groups: —CF₂—, —CF₂CF₂—, —CF₂CF₂CF₂—, —CF₂(CF₃)CF—; when R_(f) contains one oxygen atom it preferably is —CF₂(OCF₃)CF—.
 5. A process according to claims 1-3 claim 1, wherein R_(f2) is a perfluoropolyoxyalkylene chain having number average molecular weight from 66 to 12,000, preferably from 100 to 5,000, more preferably from 300 to 2,000.
 6. A process according to claim 5, wherein when R_(f2) is a perfluorooxyalkylene chain it is preferably selected from the following structures: a) —(CF₂CF₂O)_(m)(CF₂O)_(n)(CF₂CF(CF₃)O)_(p)(CF(CF₃)O)_(q)—; b) —(CF₂O)_(n)(CF₂CF(CF₃)O)_(p)(CF(CF₃)O)_(q)—; c) —(CF₂CF₂O)_(m)(CF₂O)_(n); wherein: m is comprised between 0 and 100 extremes included; n is comprised between 0 and 50 extremes included; p is comprised between 0 and 100 extremes included; q is comprised between 0 and 60 extremes included; m+n+p+q>0 and the number average molecular weight of R_(f2) being in the above limited.
 7. A process according to claim 6, wherein R_(f2) is a perfluorooxyalkylene c), and the m/n ratio ranges from 0.1 to 10, n being different from zero and the number average molecular weight comprised within the above limits.
 8. A process according to claims 1-7 claims 1, wherein in formula (I) R_(h) and R_(h2) having the following meansings meanings: —CH₃, —CH₂CH₃, —CH₂CH₂CH₃, —CH(CH₃)₂, —CH₂CH═CH₂.
 9. A process according to claims 1-8 claim 1, wherein the ion fluoride compound is any compound capable to generate ion fluorides when, in the presence of dipolar aprotic solvents, at temperatures from 20° C. up to 200° C., said dipolar aprotic solvents being acetonitrile, dimethyl-formamide, glyme, ethylene polyoxides dimethylethers (PEO-dimethylethers).
 10. A process according to claim 9, wherein the ion fluoride compound is selected from the group comprising metal fluorides, preferably alkaline or alkaline-earth metal fluorides; AgF; alkylammoniumfluorides, alkylphosphonium-fluorides, wherein the nitrogen and respectively the phosphor atom can be substituted with one or more C₁-C₈ alkyl groups, equal to or different from each other.
 11. A process according to claims 9-10 claim 9, wherein the ion fluoride compound is CsF and KF.
 12. A process according to claims 9-11 claim 9, wherein the catalyst is optionally supported.
 13. A process according to claims 1-12 claim 1, wherein the catalyst amounts, expressed in % moles, are in the range 0.1%-50% with respect to the mono- or bifunctional carbonyl compound of formula (IV). 